Thermal measuring and testing – Leak or flaw detection
Patent
1997-09-29
2000-09-12
Bennett, G. Bradley
Thermal measuring and testing
Leak or flaw detection
G01M 300
Patent
active
061167762
DESCRIPTION:
BRIEF SUMMARY
This invention relates to the detection of irregularities on or in the wall of a vessel, such as a food processing vessel for example, In one application, the invention is useful for detecting bacterial growth, and therefore of assessing the efficiency of cleaning of a food vessel, enabling contamination to be remedied. In another application of the invention, structural faults in the vessel wall may be detected for subsequent remedy, by identifying leaks or thin regions from the temperature distribution to which they give rise locally, The invention is useful in the detection of the presence of bacterial in any industrial plant and equipment. It is useful for the detection of leaks in vessels such as storage tanks processing equipment, and in refrigerated vehicles and rooms.
Vessels used to store or hold liquid products are prone to leaks, mainly caused by ageing. The impact of such leaks on the product varies according to the use of the vessel. In some cases serious contamination of the product can occur, which can lead to the product being discarded or recalled from retail outlets, either of which can be very costly.
In each case there is also a significant cost in diagnosing the leak, finding it, and rectifying it using traditional methods, Present preventative techniques often involve the shutting down of a plant or process, and the erection of expensive access equipment is often required. In addition, known techniques involving the use of dye penetrants to cover internal surfaces of the vessel can result in a leak being missed due to the dye being washed out of the flaw during removal of the excess dye.
One of the aims of the invention is to improve on the method of defect detection, including mitigating some or all of the disadvantages mentioned above.
Further, in any industry where freedom from bacteriological contamination is important, continual and sustained attention must be given to physical cleanliness and periodic sterilisation to ensure no traces of bacteria remain in preparation and receiving vessels, process plant, implements, transportable containers, and like instruments of activity.
Much industrial plant is of complex internal design, and although "CIP"--an industrial cleaning process--may be done methodically and thoroughly, a risk remains that the CIP cleaning agents have not been totally effective on all surfaces, corners and crevices of containers or implements. This problem has stimulated the formulation of this invention, which although usable on industrial plant after a cleaning operation to check the effectiveness of that operation, can usefully be employed to seek and find bacterial growth in any susceptible environment.
An aim of the present invention is to check for the presence of bacteria in, as a non-limiting example, a vessel in an industrial establishment after CIP work.
The invention provides a method as defined below. It also provides thermal imaging apparatus specifically set up to perform this method; and thermographs produced by the method of the invention, useful for locating and remedying the contaminant or the leak or other defect in or on the vessel wall.
In order that the invention may be better understood, examples will now be given with reference to the accompanying drawings, in which:
FIG. 1 is a diagrammatic sectional view of a non-jacketed food processing vessel undergoing testing in accordance with a preferred form of the invention;
FIG. 2 and 3 are views corresponding to the view of FIG. 1, of a jacketed vessel undergoing two different forms of test in accordance with the invention;
FIG. 4 is a diagrammatic sectional view of an insulated compartment of a vehicle, undergoing another form of the testing method of the invention;
FIG. 5 is a half-tone reproduction in black and white of five coloured infra-red thermographs of different defects;
FIG. 6 is a half-tone reproduction in black and white of an infra-red thermograph of a stainless steel plate with bacterial growth on it.
Referring firstly to FIG. 1, a single-skinned food processing vessel 1 has a pr
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Bennett G. Bradley
Somerset Technical Laboratories Ltd.
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